Relationship between the volume of cases and in-hospital mortality in patients with cardiogenic shock receiving short-term mechanical circulatory support.

BACKGROUND

We examined the relationship between annual case volume at each hospital and outcome in cardiogenic shock (CS) patients receiving mechanical circulatory support (MCS) devices.

METHODS

This cross-sectional study used the Japanese nationwide database to identify patients receiving short-term MCS for CS between April 2012 and March 2020. Of 65,837 patients, 3 subcohorts were created; the intra-aortic balloon pump (IABP) alone (n = 48,643), the extracorporeal membrane oxygenation (ECMO) (n = 16,871), and the Impella cohorts (n = 696).

RESULTS

The median annual case volume was 13.5 (7.4-22.1) in the IABP alone cohort, 6.4 (3.4-11.0) in the ECMO cohort, and 7.5 (4.0-10.7) in the Impella cohort. The highest quintile for the volume of cases in the IABP alone and ECMO had the lowest in-hospital mortality (IABP alone, 25.1% in quintile 1 vs 15.2% in quintile 5; ECMO, 73.7% in quintile 1 in 67.4% in quintile 5). Adjusted ORs for in-hospital mortality decreased as case volume increased (IABP alone, 0.63 [0.58-0.68] in quintile 5; ECMO, 0.73 [0.65-0.82] in quintile 5, with the lowest quintile as reference) but did not decrease significantly in the Impella (0.90 [0.58-1.39] in tertile 3, with the lowest tertile as reference). In the continuous models with the case volume as a continuous variable, adjusted ORs for in-hospital mortality decreased to 28 IABP cases/year and 12 ECMO cases/year. They did not decrease or became almost flat above that.

CONCLUSIONS

Higher volumes of IABP and ECMO are associated with a lower mortality. There is an upper limit to the decline. Centralizing patients with refractory CS in a particular hospital might improve patient outcomes in each region.